This study intends to evaluate dynamic respiratory motor performance as a valuable measure of pulmonary function in adults with late-onset Pompe disease. The investigators will adopt a strategy that includes comprehensive evaluations of respiratory volume, flow, and timing parameters during resting and loaded breathing. These evaluations will then be associated to the standard clinical measure of maximal inspiratory pressure, the static inspiratory muscle function, as well as magnetic resonance imaging of thoracic expansion and diaphragmatic descent at rest and with exertion. Outcomes in participants with late-onset Pompe disease will be contrasted to the function of age- and gender-matched control subjects. This approach will enable the investigators to evaluate the relationship between dynamic diaphragmatic function and respiratory motor function.
The following tests will be completed over a two-day period: Respiratory pressure tests, breathing test, magnetic resonance imaging and magnetic resonance spectroscopy (MRI and MRS).
Study Type
OBSERVATIONAL
Enrollment
14
Imaging of the diaphragm will be completed during resting breathing, and then during a maximal voluntary ventilation maneuver.
Upright forced vital capacity (FVC)
A spring-loaded pressure device will resist inspiration. The patient must generate the threshold inspiratory pressure to receive airflow. The changes in breathing timing, flow and volume will be recorded.
Measure the maximal airflow on inhalation
The breathing pattern will be assessed when the subject is seated and in a relaxed state.
Evaluates the time limit that a participant can maintain ventilation while breathing with a submaximal inspiratory threshold load.
University of Florida
Gainesville, Florida, United States
Inspiratory Load Compensation - Inspiratory Volume
For ILC testing, a commercially available, spring-loaded device provided a pressure load to inspiration that is independent of inspiratory flow. The patient had to generate enough threshold inspiratory pressure in order to receive airflow. The tension of the spring was adjusted to regulate the threshold pressure of the imposed load. Volume, flow and timing responses were evaluated to an inspiratory threshold load equivalent to 40% of PImax.
Time frame: Day 1
Respiratory Muscle Endurance Task
Endurance was evaluated by identifying the time limit (Tlim) that a participant could maintain ventilation while breathing with a submaximal inspiratory threshold load. The test begin after a one-hour rest. After reaching a steady state breathing pattern (e.g. stable tidal volumes for \>30 seconds), a threshold inspiratory load equivalent to 40% of PIMAX was placed on the inspiratory port of the mouthpiece. During the loaded breathing condition, the respiratory rate was set to each subject's self-selected resting breathing rate. The perceived exertion was monitored, and subjects received encouragement to maintain the target rate and mouth pressure. Encouragement was provided to maintain the established breathing pattern and to continue to task failure. The test ended when the subject could not open the threshold valve for three consecutive breaths.
Time frame: Day 2
Inspiratory Load Compensation - Inspiratory Flow
For ILC testing, a commercially available, spring-loaded device provided a pressure load to inspiration that is independent of inspiratory flow. The patient had to generate enough threshold inspiratory pressure in order to receive airflow. The tension of the spring was adjusted to regulate the threshold pressure of the imposed load. Volume, flow and timing responses were evaluated to an inspiratory threshold load equivalent to 40% of PImax.
Time frame: Day 1
Inspiratory Load Compensation - Inspiratory Time
For ILC testing, a commercially available, spring-loaded device provided a pressure load to inspiration that is independent of inspiratory flow. The patient had to generate enough threshold inspiratory pressure in order to receive airflow. The tension of the spring was adjusted to regulate the threshold pressure of the imposed load. Volume, flow and timing responses were evaluated to an inspiratory threshold load equivalent to 40% of PImax.
Time frame: Day 1
Thoracic MRI
Chest wall and diaphragmatic motions was measured in three planes with dynamic magnetic resonance imaging (MRI). The cradio-caudal change in diaphragm excursion between full inspiration and full expiration (representing diaphragm descent) was measured in the frontal plane. The anterior-posterior change in the area of the right and left sides of the chest cavity was measured in the sagittal plane (representing chest expansion). Diaphragm and chest excursion was recorded dynamically during 30-second periods of resting breathing and deep breathing.
Time frame: Day 1
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